The present invention relates to a filtration apparatus and, more particularly, to an industrial filtration system having a filter tank with a filter media movable along inside walls and the bottom thereof, the filter media separating an outlet chamber from the filter tank.
One type of industrial filtration apparatus or system includes a tank having sloped front, bottom and rear walls joined by side walls to form the tank. An inlet device to supply unfiltered liquid to the filter tank is provided. An outlet chamber or vacuum box is usually located below the filter tank adjacent the bottom wall thereof. The outlet chamber is separated from the bottom wall of the filter tank by a perforated plate. A movable filter media, usually of the replaceable fabric type, is fed into the filter tank, downwardly along the rear wall thereof, along the bottom wall such that any unfiltered liquid must pass through the filter media to enter the outlet chamber, and upwardly along the sloped front wall of the filter tank and outwardly therefrom for disposal of the used filter media. A chain flight assembly is typically provided in such filter devices. The chain flight assembly comprises two endless chain assemblies located adjacent each side wall of the filter tank; the chain assemblies are joined by flights. The chain flight assembly is movable by a drive mechanism inwardly from and adjacent the filter media along the rear, bottom, and sloped front wall of the filter tank. As the chain flight assembly is endless, a return path for the assembly is provided above the unfiltered liquid in the filter tank.
It is possible for such filter devices to operate by gravity wherein the unfiltered liquid passes through the filter media into the outlet chamber without further assistance. However, most typically such filter devices include a pump attached to a discharge from the outlet chamber. Accordingly, a pressure differential can be established across the filter media thereby increasing capacity and flow rate of the filter device. Such a filter device is shown in U.S. Pat. Nos. 3,087,620 and 4,192,747.
One problem with such filtration devices is the tendency for unfiltered liquid to bypass the filter media and enter the outlet chamber without being filtered. This especially occurs at the rear of the filter wherein the filter media and chain flight assembly are traveling vertically downwardly along the rear wall of the filter tank. Such bypassing is believed to occur by the unfiltered liquid going around the edges of the filter media wherein the unfiltered liquid then flows under the media and enters the outlet chamber without flowing through the filter media.
Accordingly, it is an object of the present invention to provide a filter device which prevents unfiltered liquid from bypassing the filter media.